[srslte-users] Prach UE in srsLTE

[Ismael Gomez]

Hi German,

Unfortunately the prach_ue example is not working properly and is not being
currently maintained. I will remove it from the current master branch.

In a few weeks we will release a complete UE (srsUE) capable to attach and
register an eNodeB and establish an IP session.

We do our internal tests with the Amarisoft LTE eNodeB only, thus we'd love
to have your feedback if you can test it with the Eurecom Open Air eNodeB.

Thanks for your valuable contribution,
Ismael

On Fri, 2 Oct 2015 at 17:35 Germán Corrales Madueño <gco at es.aau.dk> wrote:

> Hello,
>
> I'm running OpenAirInterface LTE eNodeB at 2.66GHz with 25RBs and the
> following PRACH Configuration:
>
>         prach_root                                = 0;
>>         prach_config_index                        = 0;
>>         prach_high_speed                          = "DISABLE";
>>         prach_zero_correlation                    = 1;
>>         prach_freq_offset                         = 2;
>>
>> Meaning that preamble format used is 0 (0.9 ms). If I try to use prach_ue
> example with:
>
> $  sudo ./prach_ue -f 2660000000 -F 2540000000 -p 2 -v
>>
>
>
> the cell is detected and preamble is transmitted:
>
>  Setting sampling rate 5.76 MHz
>>  - Cell ID:         0     1.8, FrameCnt: 0, State: 1
>>  - Nof ports:       1
>>  - CP:              Normal
>>  - PRB:             25
>>  - PHICH Length:    Normal
>>  - PHICH Resources: 1/6
>>  - SFN:             84
>> Decoded MIB. SFN: 84, offset: 1
>> Send prach sfn: 85. Last frame time = 11.728130, send prach time =
>> 11.738130
>> Looking for RAR in sfn: 86 sf_idx: 4
>>
>>
> However no RAR is received, which is to be expected since the eNB does not
> detect preamble activity. When I looked into the output signal of the UE
> (srsLTE) in the spectrum analyzer, I could see the envelope spanning for
> almost 8ms (8x times longer than expected). Image below...
>
> [image: Imágenes integradas 1]
> Envelope View: http://pasteboard.co/14TY5GgX.png
> Spectrum View: http://pasteboard.co/14TO4mot.png
>
> Next week I will look into the code, but I would be nice to know if
> prach_ue is operational.
>
> Thanks,
> Germán
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